Corticosteroids have been used for the treatment of various dermatoses when applied topically. The steroids have been formulated as creams, ointments, lotions and aerosol sprays. Of the various formulations, ointments have in the past received the least patient acceptance. Ointments do, however, have the beneficial therapeutic affect of occlusiveness, a highly desirable characteristic for topical steroid therapy.
Early ointment formulations used in topical steroid therapy were based largely on fats, grease and petrolatum. Early synthetic bases for use in ointments are described in U.S. Pat. Nos. 2,627,938 and 2,628,187 which describe a petroleum oil vehicle which has been thickened with polyethylene. Although these vehicles have gained wide acceptance in the steroid field they do have serious disadvantages. Cosmetically they are not as elegant as patients would like. More specifically, they impart a lingering greasy feeling to the skin, which is most noticeable on hairy skin. These ointment bases are also water insoluble and, therefore, difficult to wash off the skin. Still further, oil bases of the past are prone to stain garments and bedding with which they come in contact.
Aside from the cosmetic problems enumerated above, ointment bases posses serious physical stability problems when petroleum vehicles are employed. Excessive temperatures can cause softening or melting of the vehicle and result in the separation of suspended components. This separation of suspended components (breaking down of the gel structure is a serious problem because uniform distribution of the active steroid ingredient is considered important for successful topical corticosteroid treatment. The steroids are not soluble in petrolatum vehicles and, therefore, a steroid suspension is the only choice for incorporation of the steroid into a petrolatum vehicle.
More recently, Carbowax, a mixture of polyethylene glycol polymers has been used as an ointment-like base. These compositions have the advantage of being water-washable, but they are still greasy and cosmetically inelegant. Furthermore, Carbowax vehicles are not occlusive.
U.S. Pat. No. 3,592,930 issued July 13, 1971, discloses an ointment-like vehicle which is said to be water-washable and occlusive and which comprises as its essential ingredients a fatty alcohol having 16 to 24 carbon atoms and a glycol. The glycol solvent is said to function as a solvent for a glycol-soluble drug or as a carrier for a glycol-insoluble drug. The fatty alcohol component is said to be "a solid component which naturally thickens the composition".
U.S. Pat. No. 3,924,004 discloses a formulation comprising a saturated fatty alcohol having from 16 to 24 carbon atoms, propylene carbonate, and a glycol solvent.